CA2395893A1

CA2395893A1 - Fibrous sheet binders

Info

Publication number: CA2395893A1
Application number: CA002395893A
Authority: CA
Inventors: Kenneth P. Kehrer; Sheldon M. Atlas; Alexander Zezin; Valentine Rogachova; Victor A. Kabanov
Original assignee: Armstrong World Industries Inc
Current assignee: Armstrong World Industries Inc
Priority date: 2001-08-20
Filing date: 2002-07-26
Publication date: 2003-02-20
Also published as: US20030116294A1; USRE42110E1; KR20030017363A; US6716312B2; US20030075292A1; JP2003147691A; EP1285993A1; MXPA02008036A; US6755938B2; RU2318088C2

Abstract

A method and composition are disclosed for providing a two-part polymer binder additive for a fibrous sheet for improving both its strength and durability. The two-part polymer binder may be added to augment organic binders to increase board strength and durability or to reduce the amount of organic binder required.
The polymers may also be added in place of conventional organic binders or added in addition to organic binders to improve sag resistance and fibrous sheet performance.

Description

The results of mechanical testing:
a*=O.SOMPa, dry state a*=0..20MPa, wet state.
Example 3 The IPEC modified composition was prepared as for Example 1, except that the 0.9g of starch was added instead of 1.8g.
The results of mechanical testing:
a*=0.38MPa, dry state 6*=0.1 OMPa, wet state (a*-value for composition including 0.9g of starch and not containing IPEC
6*=0.20MPa, dry state a*=O.OSMPa, wet state).
Example 4 The IPEC modified composition was prepared as for Example 2, except that the composition included 0.9g of starch instead of 1.8g.
The results of mechanical testing:
a*=O.SOMPa, dry state 6*=0.25MPa, wet state.

Example 5 The IPEC modified composition was prepared as for Example l, except that the composition included 0.9g of starch and 0.48g IPEC(PAA-PDADMAC), ~ as a modifier. l2ml O.1N aqueous solution of sodium poly(acrylate) (NaPA) (O.llg of S NaPA), 24m1 O.1N aqueous solution of PAA (0.173g of PAA) and 12m1 O.1N
aqueous solution of poly(N,N-dimethyl-N,N-diallylammonium chloride) (PDADMAC) (0.194g of PDADMAC) were added under stirring. 0.018g of flocculant in the form of 0.2wt.% aqueous dispersion was added last.
The results of mechanical testing:
a*=0.60MPa, dry state a*=0.30MPa, wet state.
Example 6 The IPEC modified composition was prepared as for Example l, except that 1 S the composition did not contain starch and 1.8g IPEC(PAA-PDADMAC), ~ was added as a modifier. 44.0 ml. 0.1N aqueous solution of sodium poly(acrylate) (NaPA) (0.42g of NaPA), 88.0 ml O.1N aqueous solution of PAA (0.63g of PAA) and 44.0 ml O.1N aqueous solution of poly(N,N-dimethyl-N,N-diallylammonium chloride) (PDADMAC) (0.71 g of PDADMAC) were added to the composition under stirring.
0.018g of flocculant in the form of 0.2wt.% aqueous dispersion was added last.
The results of mechanical testing:
a*=0.70MPa, dry state 6*=0.40MPa, wet state.
IS

The results of mechanical testing of the compositions in terms of the values of stress at break (MPa) are listed in Table 3 and Figure 4. Figure 4 and Table 3 illustrate the effects of starch and IPEC modifier compared to starch alone and IPEC alone, on the mechanical characteristics of the composition prepared in the "brewing regime."
Table 3 IPEC Data Starch IPEC Total binderStress at Stress (g) (g) (g) break at break a* dry (Mpa)6* wet (Mpa) Control 0 0.5 0.5 0.4 0.3 IPEC alone0 0.9 0.9 0.5 0.35 0 1.2 1.2 0.6 0.4 0 1.8 1.8 0.7 0.4 0 2.7 2.7 0.85 0.45 Control2 0.5 0 0.5 0.15 0.1 Starch 0.9 0 0.9 _ _0.2 0.05 alone 1.2 0 1.2 0.25 0.0?

1.8 0 1.8 0.35 0.1 2.7 0 2.7 0.55 0.25 Combination0.5 _ 0.3 0.8 0.5 3 ~

0.5 g 0.5 0.5 I 0.65 0.4 Starch plus varied0.5 0.9 1.4 0.7 0.4 IPEC
Combination0.9 0.15 1.05 0.38 0.1 0.9 g 0.9 0.3 1.2 0.5 0.25 Starch 0.9 0.5 1.4 0.6 0.3 plus varied IPEC

Combination1.2 0.3 1.5 0.5 0.25 1.2 g 1.2 0.5 1.7 _0.6 0.3 Starch plus varied1.2 0.9 2.1 0.7 0.35 IPEC

Combination1.8 0.15 1.95 0.45 0.15 I

1.8 g 1.8 0.3 2.1 0.5 0.2 Starch 1.8 0.5 2.3 0.6 0.25 plus varied I PEC

PESC (Surfactant) Examples In the following examples, polyelectrolyte-surfactant complexes (PESC) additives where added to a basic mix of fiberboard components. The mechanical characteristics of the compositions containing different amounts of starch and PESC
S additives are illustrated in the examples. The basic components for the fiberboard were prepared in the brewing regime and were added in the following amounts:
Newsprint 6.6g Mineral Wool 4.5g Perlite 17.1 g Starch 0-2.7g Flocculant 0.018g 0.001 N KCl aqueous solution 1000g Example 7 Mineral wool, starch, perlite and newspaper were mixed as described in Example 1. Polyelectrolyte-surfactant complex (PESC) formed by partially neutralized poly(acrylic acid) (PAA) and dodecyltrimethylammonium bromide (DDTMAD) was used as a modifier. 3.6m1 0.1N aqueous solution of sodium poly(acrylate) (NaPA) (0.034g of NaPA) and 7.2m1 O.1N aqueous solution of PAA
(0.052g of PAA) were added under stirring. 9.0 ml 0.04N aqueous solution of DDTMAB (0.11g) was added and stirred for 2 minutes. Thus, 0.2g of PESC(PAA-DDTMAB), ~=[carboxylic groups]/[amine groups]=3.0 was added to the composition as a modifier. 0.018g of flocculant in the form of 0.2wt.% aqueous dispersion was added last by a plastic syringe.
The mixture was filtered with a Buchner funnel and dried in the "starch-brewing" regime as described in Example 1.
The results of mechanical testing:
a*=O.SOMPa, dry state a*=0.30MPa, wet state.
Example 8 The PESO modified composition was prepared as described in Example 7, except that DDTMAB was added first.
The results of mechanical testing:
a*=0.47MPa, dry state 6*=0.29MPa, wet state.
Example 9 The PESC modified composition was prepared as described in Example 7, except that 0.144g of PESC(PAA-DDTMAB), ~=[carboxylic groups]/[amine groups]=1.0, was added as a modifier. 3.6m1 O.1N aqueous solution of sodium poly(acrylate) (NaPA) (0.034g of NaPA) and after that, 9.0 ml 0.04N aqueous solution of DDTMAB (0.11 g) was added under stirnng.
The results of mechanical testing:
6*=O.SOMPa, dry state 6*=0.30MPa, wet state.

Example 10 In this example the PESC was added without the addition of starch. The stoichiometric complex formed by sodium polyacrylate (NaPA) and dodecyltrimethylammonium bromide (DDTMAB) named as PESC, cp=1, as well as the nonstoichiometric PESC, cp=3.0 containing a threefold excess of poly(acrylic acid), were used.
Newsprint, mineral wool and perlite were mixed in 1000 ml of warm (40° C) 0.001 N KCl aqueous solution under stirring. Then, 0.1 N NaPA aqueous solution and the corresponding amount of 0.04 N aqueous solution of DDTMAB were added under stirring for about 2-3 minutes. In the case of PESC, cp=1 the equimolar amounts of NaPA and DDTMAB were added. In the case of PESC, cp=3.0, the predetermined amount of 0.1 N aqueous solution of partially (one third) neutralized poly(acrylic acid), and corresponding amount of DDTMAB were consequently added under stirring for about 2-3 minutes. The flocculant in the form of 0.2 wt.% aqueous solution was added last by means of quick injecting it by plastic syringe.
The obtained mixtures were filtered with a Buchner funnel. The samples were enveloped in aluminum foil and kept at 177° C for 1 hour and unwrapped and dried at 177° C for 1 hour.
The wet compositions were prepared via equilibration with water vapor at 95% relative humidity (95 RH) saturated solution of KN03 in distilled water at 20° C) in the dessicator for 14 days. The samples were taken out the dessicator and were cut into 5-6 strips in the form of parallelepipeds with the length 100 mm, the width 10 mm and the thickness 8-10 mm. These strips were kept at 95 RH for 24 hours.
All the mechanical tests were carried out just after taking the strips out the dessicator using UTS-10 dynamometer (Germany) with the gauge length 70 mm.
The results of mechanical testing of the compositions in terms of the values of stress - at break, a* (MPa) are listed in the Table 4, control I and control 2 sections.
Table 4 illustrates the effects of PESC (PAA-DDTMAB) c~=1, cp=3.0 (cp=[PAA]/[DDTMAB]) as binders on the mechanical characteristics of the composition prepared in the "brewing regime." All samples contain 6.6 g of newsprint, 4.5 g of mineral wool, 17.1 g of perlite and 0.018 g of flocculant.
The samples did not contain starch. The samples were teste3 in dry and wet state.
The strengthening effect of PESC, cp=1 and PESC, c~3.0 used as co-binders together with the starch was also tested. The procedure of the preparation of the composition was the same as described above; however, the only difference is the variable amount of the starch. The samples for mechanical testing were prepared in the "starch brewing" regimes and were tested in the dry as well as in the wet state.
The results of mechanical testing of compositions containing the starch binder and PESC, cp=I or PESC, cp=3.0 co-binders are listed in Table 4 under combinations.
Table 4 and Figures 5 and 6 illustrate the joint action of starch binder and PESC
(PAA-DDTMAB) cp=1, cp=3.0 co-binder on the mechanical chaxacteristics of the compositions prepared in the brewing regime. All samples contained 6.6 g of newsprint, 4.5 g of mineral wool, 17.1 g of perlite and 0.018 g of flocculant.
The samples were tested in dry and wet state.

Table 4 Polyelectrolyte-Surfactant Complexes (PESC) Data Starch PESC Total binderStress at Stress (g) (g) (g) break at break 6* dry (Mpa)a* wet (Mpa) Controll 0 0.9 0.9 0.25 _0.1 PESC (1:l)0 1.2 _1.2 0.1 0.1 alone 0 1.8 1.8 0.15 0.1 0 2.7 2.7 0.3 0.3 Control2 0 0.9 0.9 0.2 0.1 ~

PESC (3:1)0 1.2 _ 1.2 0.25 0.1 alone 0 1.8 1.8 0.5 0.35 0 2.7 2.7 0.55 0.5 Control3 0.5 0 0.5 0.15 0.1 Starch 0.9 0 0.9 0.2 __ alone 0.05 (same 1.2 0 1.2 0.25 0.07 data as in Table 1.8 0 I_.8 0.35 O.I

3) 2.7 0 2.? 0.55 0.25 Combination0.9 0.15 1.05 0.2 0.15 0.9 g 0.9 0.3 1.2 0.3 0.15 Starch plus varied0.9 0.5 1.4 0.25 0.15 PESC (1:1)0.9 0.9 1.8 0.2 0.2 Combination0.9 0.1 S 1.05 0.2 0.2 0.9 g 0.9 0.3 1.2 0.4 0.2 Starch plus varied0.9 0.9 1.8 0.35 0.3 PESC (3:1)0.9 0.5 1.4 0.25 Combination1.8 0.1 S 1.95 0.4 0.2 1.8 g 1.8 0.3 2.1 0.5 0.25 Starch plus varied1.8 0.5 2.3 0.6 0.25 PESC (1:1) CombinationI.8 0.1 S 1.95 _0.5 0.3 1.8g Starch1.8 0.3 _ 2.1 0.6 0.25 plus varied1.8 0.5 2.3 0.8 0.3 -PESC (3:1)I.g ~ 0.9 ~ 2.7 0.6 0.3 ~

The strengthening effect of mixed IPEC+PESC co-binder in "starch brewing"
regime was also tested. Nonstoichiometric mixed IPEC (PAA-PDADMAC) + PESC
(PAA-DDTMAB), cp=3.0 was used. It was prepared as follows:
The predetermined amount of 0.1 N aqueous solution of partially neutralized (a+0,33) poly(acrylic acid) and then correspond-ing amount of 0.04 N aqueous solution of the equimolar mixture of PDADMAC and DDTMAB were added under stirring for about 2-3 minutes.
The compositions containing 0.9 g of the starch binder and different additives of mixed (IPEC+PESC), c~=3.0 co-binder were tested mechanically in the dry and wet S state. The results of the latest measurements are listed in Table 3. Table 3 illustrates the joint action of starch binder and mixed IPEC (PAA-PDADMAC) + PESC (PAA-DDTMAB), cp=3.0 (cp=[PAA]/[DDTMAB+PDADMAC] at [DDTMAB]=[PDADMAC]) co-binder on the mechanical characteristics of the compositions prepared in the "brewing" regime. All samples contained 6.6 g of newsprint, 4.5 g of mineral wool. 17.1 g of perlite and 0.018 g of flocculant.
The samples were tested in dry and wet state.
Table 5 IPEC and PESC Combinations as Starch Modifiers No. Amount of Amount of IPEC+PESC,Sample a*, MPa starch, state g ~p=3.0 I 0.9 0 dry 0.2 wet 0.1 2 0.9 0.15 dry 0.3 (0.5) wet 0.2 3 0.9 0.3 dry 0.35 (0.6) wet 0.2 4 0.9 0.5 dry 0.4 (0.7) wet 0.2 5 0.9 0.9 dry 0.4 wet 0.2 Cross-linked Interpolyelectrolyte Complexes (#IPEC) In the following examples, the effect of slightly cross-linked polyelectrolyte and linear polyelectrolyte on the mechanical characteristics of the compositions is illustrated. We used the commercial microgel of slightly cross~linked highly water swollen technical poly(acrylic acid) "Carbopol" 2001. The procedure of preparation of gel sample was the following: The predetermined amount of the dry "Carbopol"
was swollen in 300 ml of tap water for five minutes. Then the calculated amount of O.1N aqueous NaOH was added to neutralize the -COOH groups of "CarbopoI" up to the degree of neutralization a=0.33 (the amount ofNaOH added was equal to 33%
relative to the -COON groups of "Carbopol." The partially neutralized "Carbopol"
was additionally swollen in water for 12 hours. The equilibrium degree of swelling, defined as the ratio of the mass of swollen gel to that of the dry gel equaled 1000. The size of the equilibrium swollen microgel particles was about 1 mm.
The standard procedure of preparation of the composition was used: Newsprint (6.6g), mineral wool (4.5g), perlite (17.1 g), and starch (0-18g) were mixed in 500 ml of warm (40°C) 0.002N KCl aqueous solution under stirring. Then 300 ml of partially neutralized "Carbopol" microgel, prepared in advance, was added to the mixture under stirring. Then the predetermined amount of O.1N aqueous solution of PDADMAC was added to make the ratio of total carboxylic groups to ammonium groups equal to 3Ø Since the carboxylic groups were previously one third neutralized, the ratio of neutralized carboxylic groups to ammonium groups thus equals 1Ø Again, an additional amount of water was added to make the total volume equal to 1000 ml. Then 0.018g of flocculant was added last. The mixtures were filtered and prepared in the "brewing regime" as usual. The results of the mechanical testing of the samples are presented in Table 6 and Figure 7.

Table 6 Cross-linked (#) IPEC Data Starch #IPEC Total binderStress at break Stress (g) (g) (g) at break a* dry (Mpa) a* wet (Mpa) Control 0 0.075 0.075 0.25 0.15 _ l 0 0.3 0.3 0.25 0.15 #IPEC
alone 0 0.5 0. 5 0.25 0.15 0 0.9 0.9 0.12 0.07 Control2 0.5 4 _ 0.5 0.15 0.1 Starch 0.9 0 0.9 0.2 0.05 alone (same 1.2 0 1.2 (1.25 0.07 data as in Table 1.8 0 1.8 0.35 0.1 3) 2.7 0 2.7 0.55 0.25 Combination0.5 0.15 0.65 0.25 0.2 0.5 g 0.5 0.3 0.8 _ Starch 0.35 0.2 plus varied0.5 0.5 1 _ 0.35 0.2 #IPEC 0,5 0.9 1.4 0.4 0.2 Combination0.9 0.075 0.975 0.5 0.2 0.9 g 0.9 _ 0.15 1.05 __ 0._55 0.3 Starch 0.9 0.3 1.2 0.4 ~ 0.3 plus varied #IPEC

Combination1.2 0.075 1.275 0.6 0.35 1.2 g 1.2 0.15 1.35 0.5 0.4 Starch 1.2 0.3 1.5 0.4 0.3 plus varied #IPEC

Combination1.8 0.075 1.875 0.8 0.5 ~

1.8 g 1.8 0.15 1.95 0.7 Starch 0.4 plus varied1.8 0.3 2.1 0.45 0.3 #IPEC

While Applicants have set forth embodiments as illustrated and described above, it is recognized that variations may be made with respect to disclosed embodiments. Therefore, while the invention has been disclosed in various forms only, it will be obvious to those skilled in the art that many additions, deletions and modifications can be made without departing from the spirit and scope of this invention, and no undue limits should be imposed except as set forth in the following claims.

Claims

1. A polymer binder for a fibrous sheet comprising:
an anionic polymer having a negative charge of between about 4 to about 12 milliequivalents per gram; and a cationic polymer having a positive charge of between about 6 to about 12 milliequivalents per gram.

2. The binder of claim 1, wherein the molar ratio of total polyanion acid groups to total polycation groups is between about 10:1 to about 1.1:1.

3. The binder of claim 2, wherein the molar ratio of anionic polymer to cationic polymer is about 3:1.

4. The binder of claim 1, wherein the molecular size of the anionic polymer is between about 10,000 to about 900,000 grams per mole.

5. The binder of claim 1, wherein the anionic polymer is crosslinked.

6. The binder of claim 5, wherein the anionic polymer has a crosslinked density of up to about 1 per 50 units.

7. The binder of claim 1, wherein the molecular size of the cationic polymer is between about 10,000 to about 900,000 grams per mole.

8. The binder of claim 1, wherein the binder forms an interpolyelectrolyte complex.

9. The binder of claim 1, further including a spacer selected from the group consisting of a polysaccharide, a hydrogel, a latex and combinations thereof.

10. The binder of claim 9, wherein the polysaccharide comprises starch.

11. The binder of claim 1, further including a surfactant.

12. The binder of claim 11, wherein the surfactant is selected from the group consisting of alkylamines, fatty amines and combinations thereof.

13. The binder of claim 1, wherein anionic polymer to cationic polymer charge ratio is about 1:1.

14. The binder of claim 1, wherein the anionic polymer is selected from the group consisting of polycarbohydrates, polyphosphates, polysulfonates, polysulfates and combinations thereof.

15. The binder of claim 1, wherein the cationic polymer is selected from the group consisting of polymeric amine.

16. The binder of claim 15, wherein the polymeric amine is selected from the group consisting of primary amines, secondary amines, tertiary amines, quaternary amines and combinations thereof.

17. The binder of claim 1, wherein the anionic polymer is weakly acidic.

18. A method of forming a fibrous sheet comprising:
forming a fibrous slurry;
mixing into the fibrous slurry an anionic polymer having a negative charge of between about 4 to about 12 milliequivalents per gram;
mixing into the fibrous slurry a cationic polymer having a positive charge of between about 6 to about 12 milliequivalents per gram; and drying the fibrous sheet to form the fibrous sheet.

19. The method of claim 18, wherein the molar ratio of total polyanion acid groups to total polycation groups is between about 10:1 to about 1.1:1.

20. The method of claim 19, wherein the molar ratio of anionic polymer to cationic polymer is about 3:1.

21. The method of claim 18, wherein the molecular size of the anionic polymer is between about 10,000 to about 900,000 grams per mole.

22. The method of claim 18, wherein the molecular size of the cationic polymer is between about 10,000 to about 900,000 grams per mole.

23. The method of claim 18, wherein the binder forms an interpolyelectrolyte complex.

24. The method of claim 18, further including a polysaccharide.

25. The method of claim 24, wherein the polysaccharide comprises starch.

26. The method of claim 18, wherein anionic polymer to cationic polymer charge ratio is about 1:1.

27. The method of claim 18, wherein the anionic polymer is selected from the group consisting of polycarbohydrates, polyphosphates, polysulfonates, polysulfates and combinations thereof.

28. The method of claim 18, wherein the cationic polymer is selected from the group consisting of polymeric amine.

29 29. The method of claim 28, wherein the polymeric amine is selected from the group consisting of primary amines, secondary amines, tertiary amines, quaternary amines and combinations thereof.

30. The method of claim 18, wherein the anionic polymer is weakly acidic.

31. A fibrous sheet comprising:
at least one type of fiber;
an anionic polymer having a negative charge of between about 4 to about 12 milliequivalents per gram; and a cationic polymer having a positive charge of between about 6 to about 12 milliequivalents per gram.

32. The fibrous sheet of claim 31, wherein the molar ratio of total polyanion acid groups to total polycation groups is between about 10:1 to about 1.1:1.

33. The fibrous sheet of claim 32, wherein the molar ratio of anionic polymer to cationic polymer is about 3:1.

34. The fibrous sheet of claim 31, wherein the molecular size of the anionic polymer is between about 10,000 to about 900,000 grams per mole.

35. The fibrous sheet of claim 31, wherein the molecular size of the cationic polymer is between about 10,000 to about 900,000 grams per mole.

36. The fibrous sheet of claim 31, wherein the binder forms an interpolyelectrolyte complex.

37. The fibrous sheet of claim 31, further including a polysaccharide.

38. The fibrous sheet of claim 37, wherein the polysaccharide comprises starch.

39. The fibrous sheet of claim 31, wherein anionic polymer to cationic polymer charge ratio is about 1:1.

40. The fibrous sheet of claim 31, wherein the anionic polymer is selected from the group consisting of polycarbohydrates, polyphosphates, polysulfonates, polysulfates and combinations thereof.

41. The fibrous sheet of claim 31, wherein the cationic polymer is selected from the group consisting of polymeric amine.

42. The fibrous sheet of claim 41, wherein the polymeric amine is selected from the group consisting of primary amines, secondary amines, tertiary amines, quaternary amines and combinations thereof.

43. The fibrous sheet of claim 31, wherein the anionic polymer is weakly acidic.